<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Title</title>

</head>
<body>
第二个页面
<input type="button" value="回去吧" id="btn"/>

<script>

  document.getElementById("btn").onclick=function () {
      history.back();//后退
  };
</script>

</body>
</html>